Apparatus and methods for packaging products into pre-formed bags are well known in the art. Typically, in the simplest embodiment thereof, such an apparatus comprises a conveyor, for example a conveyor belt, for carrying the products to be packaged from a loading portion to a packaging portion thereof and a bag dispensing device housing a plurality of pre-formed bags and able to continuously provide an open bag. All the bags of said plurality of bags are housed in a single box and are substantially, identical each other. The bag dispensing device is placed in proximity of a free end of the packaging portion of the conveyor belt. In operation, each product to be packaged is loaded by the operator(s) onto the conveyor belt and moves toward the packaging portion thereof; when the product approaches the free end of the packaging portion of the conveyor belt, a pushing member (or an operator) pushes the product into the open bag. The apparatus is then ready for the packaging of a following product; in the meantime, the packaged product is delivered to following processes, such as, for example, vacuumization, sealing or clipping, heating and shrinking processes.
In other conventional apparatus, the bag dispensing device is not placed in proximity of the free end of the packaging portion of the conveyor belt, but at a different position. In operation, when the product approaches the free end of the packaging portion of the conveyor belt, the operator picks the bag up from the bag dispensing device, moves it close to the free end of the packaging portion of the conveyor belt and push the product into the bag.
Sometimes, especially for food, products, it would be desirable to package products of different dimensions and shape into pre-formed bags having appropriate size and/or shape. In particular, in some packaging processes, the bag containing the product is vacuumized, closed by sealing or clipping, and then heat-shrunk. This is aimed at increasing the shelf-life of the packaged product and/or improving the aesthetic appearance of the package. Bags of heat-shrinkable thermoplastic material are employed in these processes but, in order to avoid the formation of small blisters of packaging material filled with the drip of the packaged product (e.g. blood or grease), it is extremely important to select the heat-shrinkable bag of the suitable size.
With this regard, conventional apparatus of the type described above lack flexibility in operation, since it does not allow the packaging of products with different shape and dimensions into bags of appropriate size and/or shape within the same production batch. In fact, in the prior art apparatus above described, a plurality of bags having all the same size and shape are available within the same production batch. When a change in size and/or shape is required, the box containing the previously used bags is replaced by a new box containing the required new-sized bags. The packaging apparatus must therefore be shut-down, reset and restarted, thus decreasing the total production yield of the apparatus.